Decoding apparatus, decoding method and program

Abstract

The present invention provides a decoding apparatus for carrying out a decoding process on a ring-R linear code. The decoding apparatus includes coded-word holding means for acquiring a coded word with a code length reduced by omission of some symbols from the coded word and for holding the coded word; known-information addition means for attaching a reliability level of each of the symbols omitted from the coded word to reduce its code length as known symbols each having a known value to the coded word held by the coded-word holding means as known information; and repetitive decoding means for repeatedly carrying out a decoding process using belief propagation on the coded word including the known information attached to the coded word by the known-information addition means.

Description

CROSS REFERENCES TO RELATED APPLICATIONS[0001]The present invention contains subject matter related to Japanese Patent Application JP 2005-050659 filed in the Japanese Patent Office on Feb. 25, 2005, the entire contents of which being incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The present invention relates to a decoding apparatus, a decoding method and a program. More specifically, the present invention relates to a decoding apparatus, a decoding method, and a program capable of enhancing decoding performance in an error correction coding technology using an algebraic technique.[0003]In the past, as a decoding method for algebraic-geometry codes such as Reed-Solomon codes or BCH (Bose-Chaudhuri-Hocquenghem) codes serving as sub-field partial codes, a method using the algebraic property of the codes and offering a good performance cost as well as a good computation cost is known.[0004]Let us assume for example that notation n denotes a code length, notation k d...

AI Technical Summary

Benefits of technology

[0053]Addressing the problems described above, inventors of the present invention have devised a decoding method capable of displaying higher decoding performance by lowering a decoder-error generation probability in repetitive decoding processing using reliabilities updated by adoption of an adaptive belief propagation technique.

[0059]It is possible to provide a configuration in which the known-information setting means assigns a sufficiently high level of reliability to each known symbol.

[0072]It is possible to provide a configuration in which the diagonalization means carries out a diagonalization process sequentially on columns of a parity check matrix on a priority basis in an execution order starting from the column corresponding to a symbol included in a received coded word as a symbol with a lowest level of reliability.

[0075]It is possible to provide a configuration in which the diagonalization means carries out a hard-decision diagonalization process by using log likelihood ratios computed by the log likelihood ratio computation means.

[0089]reliability levels of some known symbols omitted from the coded word to reduce the length of the coded word as known symbols each having a known value are attached to the coded word held in the coded-word holding means as known information; and

[0091]In accordance with the present invention, it is possible to implement an error correction coding technology adopting an algebraic technique. In particular, the decoder-error generation probability can be lowered and higher decoding performance can thus be obtained.

Problems solved by technology

This technique does not keep up with a case of handling an uncoded portion eliminated from a shortened coded word as a portion including symbols exempted from a coding process.

Such an error correction system has a problem of the need to find out a higher-performance decoding method capable of reducing the number of error generations.

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